An actuator manufacturing method includes alternately stacking a plurality of dielectric elastomer layers and a plurality of conductive rubber layers along the direction of thickness to form a sheet, and wrapping the sheet formed about a core to form a rolled sheet. When the sheet formed in the step of alternately stacking is wrapped about the core, the sheet is formed by the dielectric elastomer layers and the conductive rubber layers. Therefore, even if the dielectric elastomer layers in the sheet are made to be thin, the thickness of the entire sheet is prevented from being excessively thin.
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7. A method for manufacturing an actuator formed by rolling a single sheet in which dielectric elastomer layers and conductive rubber layers are stacked along a direction of thickness, wherein, when a voltage is applied to the conductive rubber layers, the actuator expands the rolled sheet along an axial direction of the rolled sheet, and when the application of the voltage is stopped, the actuator contracts the rolled sheet along the axial direction, the method comprising;
alternately stacking a plurality of dielectric elastomer layers and a plurality of conductive rubber layers along a direction of thickness, thereby forming the single sheet; and
wrapping the single sheet formed in the step of alternately stacking about a core, thereby obtaining the rolled sheet, wherein
the step of wrapping the single sheet includes:
prior to wrapping of the single sheet about the core, providing a coil spring on an outer circumferential surface of the core, and providing a pair of pipes on the outer circumferential surface of the core, each pipe being at one of both ends along the direction of expansion and contraction of the spring; and
removing the core from the rolled sheet after wrapping the single sheet about the core, which has, on the outer circumferential surface thereof, the coil spring and the pipes.
4. A method for manufacturing an actuator formed by rolling a single sheet in which dielectric elastomer layers and conductive rubber layers are stacked along a direction of thickness, wherein, when a voltage is applied to the conductive rubber layers, the actuator expands the rolled sheet along an axial direction of the rolled sheet, and when the application of the voltage is stopped, the actuator contracts the rolled sheet along the axial direction, the method comprising;
alternately stacking a plurality of dielectric elastomer layers and a plurality of conductive rubber layers along a direction of thickness, thereby forming the single sheet; and
wrapping the single sheet formed in the step of alternately stacking about a core, thereby obtaining the rolled sheet, wherein
the step of alternately stacking includes
supplying one of the conductive rubber layers for being connected to a positive terminal of a power source that is formed on a front face of one of the dielectric elastomer layers, and one of the conductive rubber layers for being connected to a negative terminal of the power source that is formed on a back face of the dielectric elastomer layer, and
in this state, the dielectric elastomer layers and the conductive rubber layers are formed in a bellows-like manner, so that the plurality of the dielectric elastomer layers and the plurality of the conductive rubber layers are stacked onto each other in the direction of thickness to form the single sheet.
1. A method for manufacturing an actuator formed by rolling a single sheet in which dielectric elastomer layers and conductive rubber layers are stacked along a direction of thickness, wherein, when a voltage is applied to the conductive rubber layers, the actuator expands the rolled sheet along an axial direction of the rolled sheet, and when the application of the voltage is stopped, the actuator contracts the rolled sheet along the axial direction, the method comprising;
alternately stacking a plurality of dielectric elastomer layers and a plurality of conductive rubber layers along a direction of thickness, thereby forming the single sheet; and
wrapping the single sheet formed in the step of alternately stacking about a core, thereby obtaining the rolled sheet, wherein
some of the conductive rubber layers are connected to a positive terminal of a power source, and the other conductive rubber layers are connected to a negative terminal of the power source, and
the step of alternately stacking includes:
supplying the conductive rubber layers for being connected to the positive terminal of the power source that are stacked onto each other while being displaced in the same direction relative to the dielectric elastomer layers; and
supplying the conductive rubber layers for being connected to the negative terminal of the power source that are stacked onto each other while being displaced in the opposite direction to the direction in which the conductive rubber layers for being connected to the positive terminal of the power source are displaced relative to the dielectric elastomer layers.
2. The method for manufacturing an actuator according to
3. The method for manufacturing an actuator according to
5. The method for manufacturing an actuator according to
6. The method for manufacturing an actuator according to
8. The method for manufacturing an actuator according to
9. The method for manufacturing an actuator according to
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The present invention relates to a method for manufacturing an actuator.
Conventionally, actuators have been known in which the actuator has a sheet formed by stacking dielectric rubber layers (dielectric elastomer layers) and conductive rubber layers along the direction of thickness. This type of actuator is operated by executing and stopping voltage application to the conductive rubber layers of the sheet so that the dielectric elastomer layers are expanded or contracted (refer to Japanese Laid-Open Patent Publication No. 2007-252132).
Such actuators are used for artificial muscles. More specific examples include an actuator disclosed in Japanese Laid-Open Patent Publication No. 2009-124875. The sheet of this actuator is rolled. Voltage application to the conductive rubber layers of the sheet is executed or stopped, so that the rolled sheet is expanded or contracted along the axial direction.
To manufacture the actuator, dielectric elastomer layers and conductive rubber layers may be stacked along the direction of thickness to form a sheet, and the formed sheet may be rolled by being wrapped about a core.
The above described actuator has a tendency in that the thinner the dielectric elastomer layers of the sheet, the smaller becomes a voltage that needs to be applied to achieve adequate operation of the actuator. To minimize the applied voltage, the thickness of the dielectric elastomer layers in the actuator is desired to be as small as possible.
However, if the dielectric elastomer layers are made thinner to meet such a demand, the sheet, which is formed by the dielectric elastomer layers and conductive rubber layers, becomes also thin. When wrapping the sheet around a core to form a rolled sheet, the wrapping can be uneven along the longitudinal direction of the core. In such a case, the load accompanying the wrapping unevenly acts on the sheet, and can act on thin parts of the dielectric elastomer layers. If the load concentrates on thin parts of the dielectric elastomer layers in the sheet, the dielectric elastomer layers are likely to be torn.
Accordingly, it is an objective of the present invention to provide a method for manufacturing an actuator in which, even if dielectric elastomer layers of a sheet are made thin, the dielectric elastomer layers are not torn when the sheet is wrapped about a core.
To achieve the foregoing objective, the present invention provides a method for manufacturing an actuator formed by rolling a sheet in which dielectric elastomer layers and conductive rubber layers are stacked along a direction of thickness. Voltage application to the conductive rubber layers of the sheet is executed or stopped, so that the rolled sheet is expanded or contracted along the axial direction. The method includes a first step, in which a plurality of dielectric elastomer layers and a plurality of conductive rubber layers are alternately stacked along the direction of thickness to form a sheet, and a second step, in which the sheet formed in the first step is wrapped about a core to form a rolled sheet.
According to the above method, in the second step, when wrapping the single sheet formed in the first step about the core to form a roll, the single sheet is formed by multiple dielectric elastomer layers and multiple conductive rubber layers. Therefore, even if each of the dielectric elastomer layers of the sheet is made thin so as to reduce the voltage applied to the dielectric rubber layers to allow the actuator to operate adequately, the thickness of the single sheet as a whole is prevented from being excessively reduced. When wrapping the single sheet around the core in the second step, the wrapping can be uneven along the longitudinal direction of the core. In such a case, the load accompanying the uneven wrapping acts on the sheet. However, the load is dispersed to the multiple dielectric elastomer layers in the sheet. This prevents the load from concentrating on one of the multiple dielectric elastomer layers in the sheet. Accordingly, the dielectric elastomer layers are prevented from being torn by concentration of the load.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
One embodiment of the present invention will now be described with reference to the drawings.
An actuator shown in
As shown in
The rolled cylindrical sheet 1 shown in
The structure of the sheet 1 will now be described with reference to
As shown in
The dielectric elastomer layers 5 and the conductive rubber layers 6 (6a, 6b) are stacked along the thickness direction as described above, and closely contact each other. The conductive rubber layers 6a for being connected to a negative terminal are stacked onto each other at the left portion in
A method for manufacturing the actuator will now be described.
The actuator manufacturing method includes a first step, in which a plurality of dielectric elastomer layers 5 and a plurality of the conductive rubber layers 6 (6a, 6b) are alternately stacked along the direction of thickness to form a sheet 1, and a second step, in which the sheet 1 formed in the first step is wrapped about a core 9 to form a rolled sheet 1. The first step and the second step will now be described.
[First Step]
In the first step, a coater 11 as shown in
Process (A): With the coater 11 fixed with respect to the direction of arrow Y3, the coater 11 applies material for forming dielectric elastomer layers 5 on the film 12 as shown in
Process (B): The coater 11 is displaced leftward as viewed in the drawing from the position of the process (A). In this state, the coater 11 applies a material for forming a conductive rubber layer 6 onto the dielectric elastomer layer 5, which has been formed on the film 12 through the process (A), while being moved along the direction of arrow Y2.
Process (C): The coater 11 is operated at the same position and in the same manner as in the process (A), so that the material for forming a dielectric elastomer layer 5 is applied onto the conductive rubber layer 6, which has been formed on the dielectric elastomer layer 5 through the process (B), as shown in
Process (D): The coater 11 is displaced rightward as viewed in the drawing from the position of the process (C) (the same position as that in the process (A)). In this state, the coater 11 applies the material for forming a conductive rubber layer 6 onto the dielectric elastomer layer 5, which has been formed on the film 12 through the process (B), while being moved along the direction of arrow Y2, as shown in
Process (E): The processes (A) to (D) are repeated for a predetermined number of times.
Through the processes (A) to (E), the dielectric elastomer layers 5 and the conductive rubber layer 6 are alternately laminated on the film 12. Accordingly, one sheet 1 is formed in which dielectric elastomer layers 5 and conductive rubber layers 6 (6a, 6b) are alternately stacked along the direction of thickness as shown in
[Second Step]
In the second step, to form a roll of the single sheet 1, the sheet 1 is wrapped about a core 9 as shown in
Before wrapping the sheet 1, a coil spring 2 is attached to the outer circumferential surface of the core 9. Also, pipes 3, 4 are attached on both ends of the outer circumferential surface of the core 9 along the expansion and contraction direction of the coil spring 2 (left and right direction as viewed in
After the sheet 1 is rolled about the core 9 in the second step, the core 9 is removed from the rolled sheet 1. At this time, the coil spring 2 and the pipes 3, 4 remain inside the rolled sheet 1. The actuator is thus manufactured.
The thickness of each dielectric elastomer layer 5 for forming the sheet 1 in the first step is determined such that, when a voltage applicable for a house hold power source is applied to the conductive rubber layers 6 (6a, 6b), the actuator is expanded by the necessary amount (more accurately, such that the rolled sheet 1 is expanded by the necessary amount along the axial direction of the rolled sheet 1). The value of a voltage applicable for a household power source is, for example, up to 100 V or up to 200 V. Further, an example of the thickness of each dielectric elastomer layer 5 is 10 μm.
The total number of layers of the dielectric elastomer layers 5 and the conductive rubber layers 6 in the sheet 1 formed in the first step is determined so as to obtain the minimum thickness (for example, 50 to 100 μm) of the sheet 1 that allows the sheet 1 to be wrapped about the core 9 in the second step without tearing the layers 5, 6.
The above described embodiment has the following advantages.
(1) In the second step, when wrapping the single sheet 1 formed in the first step about the core 9 to form a roll, the single sheet 1 is formed by multiple dielectric elastomer layers 5 and multiple conductive rubber layers 6 (6a, 6b). Therefore, even if each of the dielectric elastomer layers 5 of the sheet 1 is made thin so as to reduce the voltage applied to the conductive rubber layers 6 (6a, 6b) so that the actuator operate adequately, the thickness of the single sheet 1 is prevented from being excessively reduced, for example, to less than 50 μm, as a whole. When wrapping the single sheet 1 around the core 9 in the second step, the wrapping can be uneven along the longitudinal direction of the core 9. In such a case, the load accompanying the uneven wrapping acts on the sheet 1. However, the load is dispersed to the multiple dielectric elastomer layers 5 in the sheet 1. This prevents the load from concentrating on one of the multiple dielectric elastomer layers 5 in the sheet 1. Accordingly, the dielectric elastomer layers 5 are prevented from being torn by concentration of the load.
(2) The conductive rubber layers 6a in the sheet 1 of the actuator are electrically connected to each other in the first step, so as to be connected to the negative terminal of the power source 8, and the conductive rubber layers 6b in the sheet 1 are electrically connected to each other in the first step, so as to be connected to the positive electrode of the power source 8. Therefore, of the electrodes for connecting the power source, the electrode for the negative terminal only needs to be attached to one of the conductive rubber layers 6a, and the electrode for the positive terminal only needs to be attached to one of the conductive rubber layers 6b. Therefore, compared to a case where conductive rubber layers 6 are separate from one another and electrodes are attached to each of the conductive rubber layers 6, the process for attaching electrodes is simplified.
(3) The thickness of each dielectric elastomer layer 5 for forming the sheet 1 in the first step is determined such that, when a voltage applicable for a house hold power source is applied to the conductive rubber layers 6 (6a, 6b), the actuator is expanded by the necessary amount (more accurately, such that the rolled sheet 1 is expanded by the necessary amount along the axial direction of the rolled sheet 1). Therefore, the manufactured actuator can be operated adequately by applying voltage from a house hold power source to the conductive rubber layers 6 (6a, 6b).
(4) The total number of layers of the dielectric elastomer layers 5 and the conductive rubber layers 6 in the sheet 1 formed in the first step is determined so as to obtain the minimum thickness of the sheet 1 that allows the sheet 1 to be wrapped about the core 9 in the second step without tearing the layers 5, 6. Accordingly, in the second step, the sheet 1, which has been formed in the first step, is wrapped about the core 9 without tearing any of the dielectric elastomer layers 5 and the conductive rubber layers 6 forming the sheet 1. Since the total number of layers in the sheet 1 formed in the first step is the minimum number required for preventing tearing of layers, the formation of the sheet 1 in the first step can be simplified as possible.
The above described embodiment may be modified as follows.
The first step may be replaced by the one that is conceptually described in
The number of layers such as dielectric elastomer layers and conductive rubber layers 6 of the sheet 1 formed in the first step may be changed as necessary.
The thickness of one dielectric elastomer layer 5 when forming the sheet 1 in the first step may be changed as necessary.
The power source 8 is not limited to a house hold power source, for example, of 100 V or 200v, but may be another type of power source such as an industrial power source that is outside the standard for a household power source.
The conductive rubber layers 6a for being connected to the negative terminal of the power source 8 may be electrically separated from each other. In this case, an electrode for being connected to the negative terminal of the power source 8 is attached to each of the separate conductive rubber layers 6a.
The conductive rubber layers 6b for being connected to the positive terminal of the power source 8 may be electrically separated from each other. In this case, an electrode for being connected to the positive terminal of the power source 8 is attached to each of the separate conductive rubber layers 6b.
Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.
Takeuchi, Hiromitsu, Maeno, Takashi, Kuriyama, Naoto, Kimura, Yoji, Nakai, Takanori, Tsuchikawa, Yutaka
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